Transportation method for wind energy converters at sea

ABSTRACT

A method and device for installing wind energy converters at sea is disclosed, whereby the wind energy converter is carried by a setup of buoyant bodies, characterized in that the wind energy converter is connected to ships by outriggers, in a way that allows to give the angle between outrigger and the vertical axis, in order to control the orientation of swimming.

CLAIM FOR PRIORITY

This application claims priority to German application number DE 10 2010 0260242.0, which was filed in the German language on Jun. 27,2010 and which is hereby incorporated by reference.

BACKGROUND OF THE

The invention relates to a method and a device for the building, the transport and the installation of offshore construction, especially wind energy converters.

BACKGROUND OF THE INVENTION

Especially wind energy converters are characterized in that the center of mass is situated high, and the wind load is large. Fore foundations of wind energy converters that utilize buoyancy, the stability is established by the anchoring, instead of the freeboard or location of weight, because ballast or freeboard would have to be much lager than for compensating the forces of mass alone.

As during the transport it is not possible to establish stability of the offshore construction by anchoring, in the following, a method is suggested, that makes the stabilization of the offshore construction at sea possible.

The method can also be used to utilize for wind energy converters that don't utilizes a floating foundation.

STATE OF THE ART

For the transport of wind energy converters, that are already completely composed to publications can serve as example: From DE 60009007T2 a method is known, to transport the fully assembled wind energy converter hanging on the crane. The crane is attached at the wind energy converter above the center of mass. Devices are suggested that take away load from structure of the wind electric converter, that may be introduced by the weight of the foundation. A disadvantage of this method is, that the crane has to carry the entire weight of the wind energy converter.

From DE60126984T2 method is known, to build up the windmill at land and transported to the see mounted on a ship by a transport stand to the places of operation.

Both methods have in common, that very expensive large special ships are needed.

From DE 10200633215B4 a buoyancy supported foundation is known, that can serve as example that is for a foundation that can be installed especially easy with the method described here.

Task of the present invention is to provide a method for a simple and low cost setup and transport of the offshore construction to the place of operation. In particular, the support devices for the installation shall be more cost efficient than for the devices known up to now.

SUMMARY OF THE INVENTION

This task is solved by a method and device for installing wind energy converters at sea, whereby the wind energy converter is carried by a setup of buoyant bodies, characterized in that the setup with wind energy converter an buoyant bodies is connected to ships by outriggers, in a way that allows to give the angle between outrigger and the vertical axis, in order to control the orientation of swimming.

The buoyant body is needed for a swimming foundation anyway. Therefore it can be used for carrying the load. The ships provide the floating stability together with the outriggers. By the outriggers it is possible to achieve a high stability also with small ships.

If it is foreseen for the device according to claim one that the angle between outrigger and vertical axis can be set in a controlled way, in order to control the orientation in that the wind energy converter is swimming, then the position can be readjusted after changes due to effects of alternated load during the setup of the wind electric generator, or a change in buoyancy. A special advantage is that the orientation of the wind energy converter can controlled while it is lowered down in a controlled way at the position of operation.

It is fertile, if the ship is pivotally connected preferably by a ball joint close, to its designed center of mass. This way the forces of the offshore construction (Wind energy converter) will add or reduce to the load of the ship only. The entire ship is becoming the freeboard of the whole assembly. The response of the ship to the see conditions is hardly influenced, because it still can move in the waves as it is constructed for. While the ship experiences mainly the influence of short waves, the whole assembly the relevant wavelength is the double of the outrigger.

It is advantageous if the outriggers (30) are attached to the mast (15) of the offshore construction below the center of gravity. This way it can already stabilize the offshore construction, while it is assembled.

It can be advantageous if the offshore construction is connected pivotally in the horizontal plane to the wind energy converter. This way forces can be avoided, and the ships can maneuvered more flexible in the harbor. Moreover useless forces are avoided this way.

In order to reduce the power, the ships need, it is useful to foresee a distance keeping device close to the pivot devices at the ship.

The outriggers may be formed by a single bar.

Alternatively the outrigger can be set up of a set on pilers. A possible setup consists of tree pillars. The first pillar is connected by a joint to the second pillar at one of there ends. The other end of the first pillar is connected to the wind energy converter, while the other end of the second pillar is connected to the supporting ship. The third pillar is pivotally connected the support ship on the on side and to the Wind energy converter, touching preferably a point lower than the first pillar. If now the connections by ropes are done between the joint between the first and the third pillar at the wind energy converter on the on hand and the end of the first pillar at the wind energy converter and a point near the ship, the angle Alpha and the vertical axis of the wind electric generator can be set.

If the ropes end at the ship via guiding system, the angle alpha can be adjusted in a controlled way.

The described method is especially useful for installation of offshore constructions with the following features. Advantageous is a buoyancy supported foundation for wind energy converters comprising a carrying unit that is connected with pendulum connecting peaces to the seabed.

The described method is especially useful for wind electric generators that are the installation with the following features. Advantageous is a buoyancy supported foundation comprising a wind energy converter, a carrying unit that is connected to seabed by hinged pillar, characterized in that the hinged pillar consist of a coating pipe and an inner pipe, whereby the inner pipe is connected to the seabed by a joint, an the other pipe is connected to the carrying unit.

The buoyancy supported offshore construction is especially advantageous if a buoyant volume is attached to the upper end of the hinged pillar, that is next to the lower end of the carrying unit. This way the horizontal forces introduced by wave are directly transfered to the buoyant body, without producing leaver arm forces on the pillar.

It is advantageous, if the hinged pillar produce the exes buoyancy responsible for the dynamic behavior of the buoyancy supported device. This way it is shore, that the joint between carrying unit and connecting elements is not loaded by the exes buoyancy.

Buoyancy supported foundation where at leas one hinged pillar has a footplate, that is accessible via the inner pipe by tools, has special advantages. This way the fixing foundation can be done by fixing the bottom plate to the ground. Fore this the tools can be introduced from above, preferably from above the water surface through the pipe.

The wind energy converter is composed on a buoyant body that is already swimming in the water. During the composing of the wind energy converter it is connected to the outriggers that are supported by ships. The angel between the outriggers in the horizontal plane is different from zero and 180°. in the vertical the angle between the horizontal axis and the outrigger is adjustable. This way the orientation of the swimming can be influenced.

At the ship the outrigger is connected pivotally at a point close to the designed center of mass, so that all loads are acting on the designed center of mass. This way the stability of the ship in the motion of the sea is hardly affected, and the whole loading capacity of the ship can be used, in order to stabilize the wind electric converter. If the wind energy converter has a mass of 700 t and the center of mass is 70 m above the center of buoyancy, at a length of the outriggers and a tilting of 20° the load on to the ship would result in 240 t that load or unload the ship.

DESCRIPTION OF THE DRAWINGS

The details of the invention will now be explained, referring to the drawings. It shows,

FIGS. 1 a,b a schematic drawing of the wind energy converter with the ships, as they are placed in the configuration for transport,

FIGS. 2 a,b,c the assembling process of the wind energy converter in the harbor,

FIG. 3 special type of foundation that is advantageous for the setup,

FIG. 4 the installation of the device special advantageous type of foundation,

FIG. 5 a to f the installation of a special foundation, that does not have buoyancy, utilizing an additional buoyant body.

DETAILS OF THE INVENTION

FIG. 1: The wind energy converter (10) is situated on the buoyant body (20), shown schematically, that is carrying at least partially the load of the buoyant body. The device is supported via the outriggers (30) on the assisting ships (40). The mounting element (31), that is used to mount the outrigger to the offshore construction can be moved in a controlled way, so that the angel between the vertical axes (11) can be adjusted in a controlled way.

On the assisting ships (40) the outriggers are attached vial pivot joints (43), that allow the outriggers to be pivoted into all directions. Fertile this pivot joint (43) is mounted close to the design location of the center of mass of the ship, because this way the response of the ship to the motion of the sea does hardly change. By it own drive an the rudder the direction of the ship can be controlled. By the ships acting together the device can be moved into every direction, and it also can be turned around its vertical axes.

The position of the vertical axes can be controlled, if the angel between the vertical axes of the wind energy converter and the outrigger is adjusted. In the example shown here the ends of the outriggers (31) are connected via joints to the rest of the outriggers. They can be tilted e.g. via a hydraulic system. By this element (31) the outriggers are fixed at the device. At any outrigger is a possibility for adjustment foreseen. The controlling is especially important, if the wind electric generator is lowered down for anchoring at the designated place of operation.

It is especially advantageous to put a distance keeper 33 between the outriggers securing, that the distance between the ships is remaining. Alternatively the distance can be kept by the designated directions in that the different ships are heading. The forces for this would be forces of the engine, and therefore would reduce the power available for other purposes. A rope can be used to control the distance in an advantageous way.

FIG. 2 a shows how the wind energy converter is composed in the harbor together with a setup of helping ships according to the invention. FIG. 2 a shows a crane (200) standing on quayside (300). On the crane is hanging a buoyant body (10) or the setup of buoyant bodies, that is to be put into the water. The buoyant body may be fixed at the quayside or on piles close to it.

FIG. 2 b shows how the segment (15) of the tower of the wind energy converter is set onto the buoyant body (20). The outriggers were connected to the outriggers (30). This connection can be performed on the quay before. In the moment, where the segment (15) is connected to the buoyant body, the the orientation in witch the buoyant body is swimming can be controlled via the outriggers an the maximum stability can be maid availably.

In the other embodiments of the invention the outriggers can be fixed to the buoyant body ore other parts of the offshore construction.

As the stability is secured by the supporting ships (40), the tower can be set up, as shown in FIG. 2 c. In this drawing tower elements (15.1) and (15.2) are mounted on top.

In FIG. 2 d the completed wind energy converter together with the setup of supporting ships is shown.

In FIG. 3 a special swimming foundation (500) in a special embodiment that is especially right for installing with the method described here.

Below the mast (15) of the wind energy converter (10) is the carrying structure (510), consisting of pipes, forming the edges of a tetrahedron. The tetrahedron points with one peek up. On this edge the mast (15) is attached. The other edges (512) are in a horizontal plane. On the edges via kadarn joints(513) connecting elements (514) to the ground (600) are mounted, witch are connected to the ground by joints as well. This way they form pendulum supports. On top of the pendulum supports buoyant bodies are mounted, that provide an essential portion buoyancy of the swimming foundation. They may produce the buoyancy for the whole offshore construction, and additional exes buoyancy, required for influencing the motion in the waves. In principle it is also possible to mount the whole offshore construction to the carrying structure (510). But it is most fertile to produce at least the exes buoyancy by the buoyant bodies (520) that are located at the connecting elements. This way the joints (512) are not loaded with the forces of the exes buoyancy. Thigh the buoyant body comprises a coating pipe (531) leading through the buoyant body, guiding an inner pipe that is forming the lower part of the connecting element. During the anchoring process the coating pipe (531) is connected to the inner pipe (532) forming the lower part of the connecting element. For the installation, the pipe can be moved up and down.

The joint (515) connects the connecting elements (514) respectively the inner pipe (532) to a foot plate (516). The joint (515) is designed such that something can be guided through the inner pipe (532) and also through the joint (515). For this purpose the joint can be built as cross joint with a ring shape cross body. This tolls and material for fixing the footplate to the ground can be fad through the inner pipe (532). Trough the inner pipe (532) A peal (540) can be driven into the ground, that is holding the footplate on the ground. The peel can also be inserted by drilling. From the state of the art there are methods known, produce a suitable anchoring at the end of such a pipe. In order to loosen the footplate connection the had of the peal (540) can be drilled out with a suitable drill.

FIG. 4 shows a buoyancy supported foundation (500) that is transported to the place of operation by from the support ships. At this time the swimming foundation is that far out of the water that the remaining buoyancy is as large as the gravitational forces. The pipes (532) are pulled upwards. On the inner pipes (532) a prolongation pipe (533) is mounted. This prolongation pipes allows to to lower inner pipes to the seabed even if the foundation is kept to the water surface by the buoyancy. For anchoring the swimming foundation, one will proceed as follows: The support ships bring the device to the place of destination. The inner pipes (532) are lowered to the ground. In order to make the feet touch the right position, the inner pipes may be connected with ropes at the bottom. If the inner pipes (532) are also connected by ropes at the top or even at the prolongation pipes (533) it can by fully controlled, where the pipes will be put on the ground. Now the feet are standing on the ground with the weight of the inner pipes. Small motion of the carrying unit will be leveled out by the motion of the joints an the free motion of the inner pipes (532) inside the coating pipes (531). Now on the inner pipe devices for the anchoring of the feet can be placed. After the anchoring of the pipes, the swimming foundation can be lowered down. [270] For this it is suitable to fill the buoyant bodies with ballast. The buoyant body will sink down, as the buoyant force is compensated. Meanwhile the support ships will secure stability by controlling the angle alpha. If the required depth of diving is reached, the inner pipe (532) is connected with the coating pipe. After that the ballast water pumped out or pressed out by compressed air.

Alternatively the carrying structure can also be pushed under the water, by applying a force between the upper end of the prolonging (533) of the inner pipe (523) and the coating pipe, preferably by a hydraulic system. Another possibility is to prolong the coating pipe also. Than the lowering can be done by hydraulic winches mounted on the prolonged coating pipe, puling via ropes on the inner pipes.

All methods have in common, that the supporting offshore construction remain above the water. This way diving work is not required. Therefore the dependence of the whether is reduced. Al support offshore constructions can be taken away after the installation and can be used again.

If the offshore construction is installed at the place of operation, the helping ship and can be loosened from the device. For this purpose the outriggers can be lowered by utilizing the crane that is usually part of most wind energy converters, after loosening the connection (31). If the outrigger has buoyancy by its own, it can be pulled behind the ships.

The method can also be applied, as shown in FIG. 5 a-f, in a modified way for building up foundations (500), that stand on the seabed and do not perches buoyancy when they are assembled. In general an additional buoyant body (800) must be foreseen for this purpose. Methods to ad such a buoyant body will be shown in the following, referring to examples of special foundations.

A group of foundations is given by the publications DE 10061916B4 and DE102004 042 066. These foundations consist of piles (650), that are driven into the ground, being connected by an additional support structure (600). This support structure is carrying the mast (15) of the wind energy converter (10). In DE 10 2004 042 066 this support structure (600) forms a stiff connection between the piles (650), in a way that transfers forces of the waves between the different piles. The transfer of forces is done by radial brace (601). Therefore forces can be induced everywhere in the radial brace (601) during the transport. In DE 100 61 9 16 a support structure is shown, consisting of a grid of multiple pillars. By joints the transfer of forces between the piles is avoided. It can be expected that forces can mainly be introduced at places close to the points close where the connection to the piles (600) is planed.

The piles (650) shell form a polygon, preferably a triangle ore a square. In the literature cited above the polygon is supposed to be a regular polygon. But it can also be useful to have an irregular polygon, where the hight of the polygon corresponds to the proffered directions of the wind and the waves.

Expedient use of the transportation method according to the invention is to transport the support structure (600) together with the wind energy converter (10). The piles (650) are driven into the seabed (2000) before.

It is foreseen that the buoyant body (800) is situated in the middle below the support structure. The buoyant structure should be more narrow than the distance between at least two neighboring of the piles (650). By this it can be maneuvered between the piles. In order to be able to put the support structure (600) on to the piles without utilizing cranes, it is foreseen that the buoyant body can vary its hight of swimming. It is required that the buoyant body in the loaded situation can lift the support structure (600) including the parts foreseen for the connection to the piles (650) above the piles (650), and it must be possible to lower the buoyant structure in the unloaded case below the support structure (600), in order to be able to pull it out of the piles (650). For this the buoyancy necessary for carrying the Wind energy converter (10) including the support structure (600) must be compensated. This can be done by water ballast. The ballast can be unloaded by pumps or by using compressed air. The buoyant body (800) should be able to take a position, where it has a low draft, in order to make it easy to operate in a harbor. For this purpose a flat shape of the buoyant body is useful.

It is advantageous if the elevation of the buoyant body (800) can by done quickly via the ballast. For this purpose it is useful, if the body (800) has a small area on the water surface. A stabilization of the orientation of swimming is not required for the transportation process, because the ships stabilize it. But it is an advantage, if the buoyant body (800) has at least that much stability, that it can keep its upright position on its own, when it is not loaded.

In order to achieve all this, it is useful to built the buoyant body as semi submersible. The main buoyant body may be set up as parallel cylindrical bodies (801). These bodies may be connected by pillars. At the ends of the pipes it is useful to foresee pipes as columns (802) that rise up. The upper end of the columns may be connected by a frame (803). On this frame the support structure (600) may be located. To secure the support structure it may be fixed by screws on the frame (803).

For mounting the wind energy converter at see one can proceed as follows: The piles (650) are driven in to the seabed already. The Wind energy converter (10) mounted on the support structure (600) is brought to the position of operation. The support structure (600) is maneuvered above the piles (650). By utilizing preferably six ropes connecting piles (650) and support structure (600), the support structure can be aliened. After the alignment, the support structure (600) can put on to the piles (650). Next an enduring connection between the piles (650) an the support structure (600) is set established. After that the buoyancy of the buoyant body is increased in order to unload the connection between buoyant body (800) and support structure (600).

If the outrigger (30) are not directly connected to the buoyant body (800) the buoyant structure can be pulled out between the piles (650) by ropes.

In an other variation of the invention, the outriggers (30) may also be directly attached to the buoyant body (800) this way it is possible to control the buoyant body (800) via the outriggers (30) during the whole transport.

It is useful to separate the buoyant body into different sections by preferably by sheets, in order to increase the stability by hindering the ballast water to move around.

For the transport of wind energy converters (10), that are foreseen for the mounting on foundations (900) that cover a relatively small area like monopiles and jackups a modification of the buoyant structure (800) may be useful. There main buoyant bodies (801) shall be connected only at the front. The frame (803) shall be open at the back as well. This wind energy converter is holden by a special mounting in the middle of the buoyant structure. It is now possible to push the wind energy converter over the foundation (900). Lowering an mounting can be done almost like described above.

The method described solves a key problem for the installation of offshore wind power: Ships that can compose wind energy converters at sea, are expensive. During the period in that large wind farms are built, there will not be enough ships, because the phase could be over before the ships have paid off. After that period ships are still required, but only for maintenance. Even, if this method would only be used for the initial setup, and not for maintenance, this bottleneck would be abandoned.

The costs for the support ships are much lower on the one hand. On the other hand ships used for fishing or tugs or even other ships can be modified. 

1. A method and device for installing wind energy converters at sea, whereby the wind energy converter is carried by a setup of buoyant bodies, characterized in that the setup of wind energy converter and buoyant body is connected to ships by outriggers, in a way that allows to give the angle between outrigger and the vertical axis, in order to control the orientation of swimming.
 2. A method and device according to claim 1 characterized in that for setting the orientation of swimming, the angle between the outrigger and the horizontal axis can be adjusted in a controlled way.
 3. A Method and a device according to claim 1 characterized in that the outrigger is connected to the individual ship by a joint, preferably a ball joint, that is preferably located close to the center of mass of the design center of mass of the ship.
 4. A Method an device according to claim 1 characterized in that the outrigger is mounted to the wind energy converter pivotally in the horizontal plane.
 5. A method and a device according to claim 1, characterized in that the outrigger the mast of the device below the center of mass.
 6. A method and device according to claim 1 characterized in that between the ships a distance keeping device is mounted between the outriggers preferably close to the joints to the ships.
 7. Buoyancy supported foundation comprising a wind energy converter, a carrying unit that is connected to seabed by hinged pillar, characterized in that the hinged pillar consist of a coating pipe and an inner pipe, whereby the inner pipe is connected to the seabed by a joint, and the other pipe is connected to the charring unit.
 8. Buoyancy supported device according to claim 7 characterized in that a buoyant volume is attached to the upper end of the hinged pillar, that is next to the lower end of the carrying unit.
 9. Buoyancy supported foundation according to claim 7, characterized in that the hinged pillar produce the exes buoyancy responsible for the dynamic behavior of the buoyancy supported device.
 10. Buoyancy supported foundation according to claim 7, characterized in that at least one hinged pillar has a footplate, that is accessible via the inner pipe by tools. 